Postprandial amino acid profiles and gastric behavior after consumption of milk and plant-based alternatives: a randomized cross-over study in healthy males

Abstract

Background: There is a growing availability of plant-based alternatives for bovine milk. However, plant-based drinks differ e.g. in protein quantity, protein quality and carbohydrate composition. Knowledge on the impact this has on digestion-related outcomes such as postprandial amino acid (AA) availability and gastric behavior is still limited. Additionally, data on milk alternatives with higher overall protein concentration are lacking. Objective: We aimed to compare the differences in postprandial AA profiles, glycemic response, and gastric behavior between bovine milk and plant-based drinks with or without added protein using representative commercial drinks. Methods: 12 healthy males participated in a randomized crossover study with three treatments. After an overnight fast, participants drank 750 ml of semi-skimmed milk (Milk), a standard oat-based drink (OBD) or an oat-based drink enriched with pea protein (OBD+Pea). Blood samples were taken for measurement of plasma AA, glucose, insulin and FGF21 over 5 hours. Gastric content changes were assessed using magnetic resonance imaging scans for Milk and OBD+Pea over 2 hours. Results: Compared with Milk, both oat-based drinks elicited lower 5-h total AA iAUC (OBD -169706; OBD+pea -139552 microM*min; both P<0.001) and EAA iAUC (OBD -91748; OBD+pea -78199; both P<0.001), with no differences between oat-based drinks. Gastric content volume was lower for OBD+Pea versus Milk from 60-120 min (range -48 - -84 ml, all P<0.001). Compared to Milk, OBD and OBD+Pea increased glucose more from 15-45 min (range 0.86 - 1.73 mmol/l, all P<0.001) and insulin from 30-60 min (1.84 - 2.14-fold, all P<0.001). Conclusions: Protein enrichment in plant-based milk alternatives can be a valuable strategy to increase protein content and improve amino acid composition. However, such products still show faster gastric emptying, lower postprandial essential amino acid and higher glycemic and insulinemic responses compared to bovine milk because of their different carbohydrate and protein content and quality.